I think that it's difficult to say whether or not itemisation will be appropriate for druids in the expansion. ap/agil/stam leather may become redundant even for feral druids if encounter design forces them to say, stop tanking when their add is dead - or stop DPS and throw a few heals during a heavy environmental damage pulse.
I also heard a rumour a while ago (sorry I can't provide a better source :P) that 'meta sockets' will alleviate some itemisation problems. Say you have a weapon with a metasocket that says "all red sockets now provide +3 healing", you can switch that in when healing, and switch to a weapon with "all red sockets now provide +3 feral AP" when going DPS or you need threat for tanking.
There's also the new stat modifier on the
priest atiesh which fixes a few more problems too - basically it makes dmg/heal in favour of the +heal. It'll be interesting to see if this stat is just reserved for some items or used more widespread, however.
Finally, meleekin may make "hybrid leather" the ideal choice for PvPers of all specs, feral druids, and balance druids. It may even end up being the case that the only types of leather are "hybrid leather" and "healing leather".
Lastly - one thing I've always found a little frustrating, having played both a druid and a hunter to 60, is the presumption that only druids have bagspace problems. On my hunter I carry a PvP set and a PvE set, and an entire quiver full of arrows (in addition to potentially resist gear). Bag space is a general problem facing a good number of players, not just druids.